In recent years the incidences of cancer in general has significantly increased. Concurrently the use of radiation therapy to treat cancer has also increased. Radiation therapy is used to treat cancer patients in two ways: for curative purposes and for palliative reasons.
Virtually all radiation therapy centers are equipped with simulators--a fluoroscopic imaging unit equipped with all the characteristics and parameters found on the radiation treatment units. With the help of diagnostic imaging such as computerized x-ray tomography (CT) and magnetic resonance imaging (MRI), when combined with the fluoroscopic capability of the simulator, a radiation therapy portal (the area through which the treating radiation will be focussed) may be designed. Conventionally, the perimeter, isocenter, and set-up points of this radiation therapy portal are marked on the patients skin with magic markers, fuchsia color, and/or tattoo markings. However, there are many problems with these conventional markers.
The time between simulation and beginning treatment is usually zero to seven days. During this period, generally greater than one day, various types of markings may be lost. For this reason, tattooing is often used to establish the portal boundaries with some permanency and reproducibility. However, there are several disadvantages to tattooing, even though it may seem to be the most optimal means to establish portal boundaries.
One problem is that tattoos are difficult to recognize on dark skin. Thus, tattoos too may be lost.
An additional problem is that the tattooing process punctures the patient's skin multiple times and, therefore, exposes radiation therapy personnel to the patient's blood and the patient's blood to out-side contaminants. This exposure creates a risk that the radiation therapy personnel or the patient may be contaminated with various infectious organisms transmitted by blood exposure, especially the autoimmune virus.
Two further problems are associated with the permanency of tattoos. First, a radiation therapy portal boundary tattoo is aesthetically unattractive. This is especially problematic when the tattoo is placed on skin surfaces which are not ordinarily covered by clothing. Second, but technically of equal importance, a radiation therapy portal boundary tattoo is inflexible. Initially, this may seem to be a benefit because it limits the risk that the portal boundary markings might inadvertently shift. However, a portal field for a particular patient is frequently changed throughout the course of treatment thereby requiring a shift in the portal boundary markings. Once tattooing marks are established a re-tattooing is required to shift the portal boundaries thereby compounding the above described disadvantages.